A. Field of the Invention
The present invention relates generally to data transmission in networks, and more particularly to systems for optimizing IP data traffic flows within network routers using a periodic dither signal to regulate the flow.
B. Description of the Related Art
Many IP or packetized network traffic models are currently based on well-established queuing models for predicting traffic loads on voice telephony networks. The fundamental reason why traffic aggregation is well understood on voice networks is that callers are refused admittance to the network once a link is saturated. In this manner, the network behaves according to stochastic Poisson statistics. The end-to-end network flows act uncorrelated and independent causing the peak to average load ratio to decrease as the number of users on the network increases. In other words, the peak to average load ratio 100 of voice calls decreases as the number of voice calls increases, as expected from white noise statistics. This phenomenon is shown in FIG. 1.
On the Internet, however, the number of users or computers that can access the network at any given time is not limited. In the event of congestion, all of the computers reduce the transmission rate of data until the congestion clears. This reduction of the flow rate due to saturation of the network results in waves of data that are known to be fractal or self-similar in nature. Self-similar means that traffic on Internet networks exhibits the same characteristics regardless of the number of simultaneous sessions on a given link. In other words, the peak to average load ratio of the traffic does not reduce to the level expected from purely Poisson statistics as the number of shared users in the medium increases. This is because there is correlation of the end-to-end flows as the number of shared users increases. FIG. 2 illustrates an example of the fractal nature of a standard IP flow 200 over time.
Referring now to FIG. 2, as a consequence of the fractal nature of the Internet, higher capacity data pipes must be built to handle peak bursts 202 in the traffic patterns. However, providing extra bandwidth to compensate for occasional peaks in the traffic patterns is inefficient and expensive.
One possible solution for improving IP flow and bandwidth efficiency of a congested IP network is to add Constant Bit Rate (CBR) services, such as voice traffic, to the network. FIG. 2 illustrates the standard IP flow 200 and an IP flow with CBR services added 250. As shown in FIG. 2, the peak to average load ratio of flow 250 decreases from that of IP networks without CBR services. This is counterintuitive because there is less total bandwidth available for the other IP traffic sharing the transmission medium. However, the IP network is basically a nonlinear, dynamic system with positive feedback. The addition of the CBR services reduces the feedback gain on the IP traffic flow, thereby reducing the peak traffic burstiness enough to increase the total IP packet flow. Although the addition of CBR services increases total IP flow, bandwidth utilization is still inefficient and undesirably costly. Therefore, what is needed in the art is a way to further improve bandwidth efficiency and IP flow in a data communications network.